Methods and equipment to make lithium hydroxide monohydrate from lithium salts

ABSTRACT

Embodiments of the invention relate to methods and equipment to make lithium hydroxide from lithium salts.

SUMMARY

Embodiments of the invention relate to methods and equipment to makelithium hydroxide, such as a lithium hydroxide solution from lithiumsalts for lithium hydroxide monohydrate production.

A method of producing lithium hydroxide from lithium salts. The methodincludes contacting a resin bed including anion exchange resin havinghydroxyl ions bound thereto with a contacting solution having dissolvedlithium salts therein for a duration of time effective to at leastpartially exchange anions of the dissolved lithium salts with thehydroxyl ions bound to the anion resin. The method includes draining thecontacting solution from the resin bed to collect a product solutionincluding at least some lithium hydroxide therein. The method includeswashing the resin bed with water effective to displace any residualcontacting solution from the anion exchange resin. The method includessoaking the resin bed with a caustic solution effective to displaceanions of the lithium salt solution from the anion exchange resin withhydroxyl ions of the caustic solution. The method includes draining thecaustic solution from the resin bed to collect a by-product solution.

A system for producing lithium hydroxide from lithium salts isdisclosed. The system includes a holding tank having a height and atleast one drain. The system includes a resin bed including an anionexchange resin therein, the resin bed having a height less than or equalto the height of the holding tank, the anion exchange resin includinghydroxide ions bound thereto. The system includes a retention memberdisposed in the holding tank between the resin bed and the at least onedrain, the retention member being configured to retain the resin bed inthe holding tank. The system includes a plurality of input lines,including a first input line operably coupled to a supply of, andconfigured to deliver, a lithium salt solution into the resin bed in theholding tank; a second input line operably coupled to a supply of, andconfigured to deliver, a caustic solution into the resin bed in theholding tank; at least a third input line operably coupled to, andconfigured to deliver, water to the into the resin bed in the holdingtank. The system includes a plurality of output containers, including afirst output container configured to hold a lithium hydroxide solutionproduced in the resin bed from interaction thereof with the lithium saltsolution; a second output container configured to hold a sodium saltsolution produced in the resin bed from interaction thereof with thecaustic solution; and at least a third output configured to hold one ormore of a wash or rinse solution from the resin bed. The system includesone or more valves and fluid lines operably coupled to the first inputline, the second input line, the at least a third input line, the firstoutput container, the second output container, the at least a thirdoutput container, and the holding tank.

Features from any of the disclosed embodiments may be used incombination with one another, without limitation. In addition, otherfeatures and advantages of the present disclosure will become apparentto those of ordinary skill in the art through consideration of thefollowing detailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate several embodiments of the invention, whereinidentical reference numerals refer to identical or similar elements orfeatures in different views or embodiments shown in the drawings.

FIG. 1 is a schematic of a system for producing lithium hydroxide fromlithium salts, according to an embodiment.

DETAILED DESCRIPTION

Embodiments of the invention relate to methods and equipment to makelithium hydroxide, such as a lithium hydroxide solution from lithiumsalts for lithium hydroxide monohydrate production. The processesdisclosed herein can be used for producing lithium hydroxide monohydratefrom lithium salts and/or purified lithium salt solutions generated fromleaching lithium ore concentrates. The processes and systems herein canbe used to temporarily sequester counterions of lithium salts (e.g.,sulfate) on an ion exchange resin to produce lithium hydroxidecontaining solution which can be further processed to yield lithiumhydroxide monohydrate. The processes and systems herein can also includereleasing the counterions of the lithium salts from the ion exchangeresin using a caustic solution (e.g., NaOH or KOH) to produce analkaline salt solution having the counterion therein. The ion exchangeresin can be washed with water between contacting the lithium saltsolution and the caustic solution. The acts of the methods can becarried out in series, which may be repeated one or more times, tocontinuously produce lithium hydroxide for lithium hydroxide monohydrateproduction.

Lithium hydroxide monohydrate can be produced from lithium salts by bothchemical and electrochemical methods. Chemically, lithium carbonate canbe converted to lithium hydroxide by reacting the carbonate salt withlime, producing a slurry comprised of a lithium hydroxide solution andprecipitated calcium carbonate. The lithium hydroxide can be separatedfrom solid calcium carbonate, evaporated using multiple effectevaporators to produce lithium hydroxide slurry, which can be furthertreated to produce dried lithium hydroxide monohydrate product.

A chemical method to make lithium hydroxide from lithium sulfatesolution may include causticisation of lithium sulfate, wherein thelithium sulfate solution is mixed with sodium hydroxide to produce asolution mixture of lithium hydroxide and sodium sulfate. From thissolution mixture, sodium sulfate can be crystallized out first and thenlithium hydroxide product. This separation is difficult and complicated.Some lithium loss occurs in this process as the by-product sodiumsulfate is separated from the lithium hydroxide and sodium sulfatesolution mixture. This is a significant drawback of the process. Afurther drawback is that even if there is no market for sodium sulfate,its production using an evaporator or drier is still required in thisprocess including its handling and disposal, adding more steps to theprocess and increasing operating costs as a result. In other words, inthis chemical process the production of lithium hydroxide is dependenton the production of sodium sulfate. The option of discarding the sodiumsulfate solution into an evaporation/tailings pond, temporarily orpermanently, to balance the market fluctuations is not available in thisprocess.

Electrochemically, lithium hydroxide can be produced from lithium saltsolutions including one or more of lithium sulfate, lithium nitrate,lithium carbonate, or lithium chloride. In the case of lithiumcarbonate, it can be first converted to lithium sulfate by reacting itwith sulfuric acid to produce a lithium sulfate solution. Electrolysisof lithium sulfate generates acid on the anode side of the cell andlithium hydroxide on the cathode side of the cell. The anode and cathodecompartments of the electrolytic cell can be separated by an ionselective membrane therebetween, such as a cation selective membrane.The acidified lithium sulfate solution can be recycled back to theprocess to dissolve more lithium carbonate, which avoids the cost ofpurchasing sulfuric acid to dissolve lithium carbonate. The electrolysisof a lithium nitrate solution is similar to that of the lithium sulfatesolution described above. In the case of the lithium chloride solutionthe anodic reaction produces chlorine gas instead of the acid, whileproducing lithium hydroxide solution on the cathode side. The chlorinegas, on burning, yields hydrochloric acid which can be recycled back toleach more lithium from lithium bearing ore concentrate. The lithiumhydroxide produced by the cell can be evaporated in multiple effectevaporators to produce dried lithium hydroxide monohydrate product.

While the electrochemical method can produce lithium hydroxide fromlithium salts including one or more of lithium carbonate, lithiumsulfate, lithium chloride and lithium nitrate, the method has somedrawbacks. The process is capital intensive, complex, requires feedsolutions to be virtually free of impurities, particularly calcium andmagnesium. The impurities (e.g., calcium and/or magnesium) tend to plugthe cation membrane used by the divided electrolytic cells comprisingthe electrochemical system, which causes them to lose efficiency or stopworking, shutting down the process due to sharp rise in the cellvoltage. This can happen immediately upon membrane plugging and cannotbe avoided. The power cost also is a serious drawback of the process atlocations where the unit power price is high. Though the electrochemicalmethod can be used to produce lithium hydroxide from lithium salts asmentioned above, the method has some drawbacks as mentioned above. Themajor benefit of the electrochemical methods is that they do notproduce—unlike typical chemical methods—any by-product to dispose of orsell.

A chemical method that is capable of producing lithium hydroxide fromany of the salts previously mentioned, that is simple, easy to operate,not capital cost intensive, saves power, and offers the options toeither produce the by-product if it has a market or discard it whenthere is no market without losing lithium values in the process, can beused to make lithium hydroxide product more cost effectively thancurrent techniques. The process and the equipment disclosed herein canbe used to meet the goals noted above, making it a unique and novelmethod to produce lithium hydroxide solution for lithium hydroxidemonohydrate cost-effectively.

Process and Related Systems

The chemical techniques described herein include an ion-exchangeprocess. The techniques and systems disclosed herein utilize anionexchange resin and sodium hydroxide to produce a lithium hydroxidesolution from a lithium sulfate solution. The lithium hydroxide solutionupon further processing yields the final product—lithium hydroxidemonohydrate. Such a process produces one by-product, sodium sulfate.

FIG. 1 illustrates a system 100 used for the techniques disclosedherein. The system 100 can include a holding tank 110, a resin bedincluding an ion exchange resin 120 housed within the holding tank 110,an agitator 130 (e.g., over-head mixer) for mixing purposes, at leastone vacuum pump 140 to help drain solutions in resin bed as much aspractical, a plurality of output containers of receivers 150 a-150 d forholding feed solutions and processed solutions, and pumps (not shown) tomove solutions.

The holding tank 110 can include one or more walls defining an interiorspace containing the resin bed 120. The holding tank 110 can include aretention member 112 disposed therein. The retention member 112 can beconfigured as a screen or frits sized and positioned to allow fluid topass therethrough while retaining the ion exchange resin of the resinbed 120 in the holding tank 110. The holding tank can include a drain114 operably coupled to one or more of the plurality of outputcontainers 150 a-d. Each of the output containers 150 a-150 d can beoperably coupled to a vacuum pump 140 to apply a vacuum to the interiorvolume thereof, such as to aid in removal of one or more solutions fromthe holding tank 110. The holding tank 110 and the output containers 150a-d can be operably coupled together via one or more valves and conduitsconfigured to provide a selectively changeable connection therebetween.For example, one or more valves may be actuated to cause a solution inthe holding tank 110 to drain into a first output container 150 a, andthen another set of valves may be actuated to cause a second solution inthe holding tank 110 to drain into a output second container 150 b, andso on. The holding tank 110 can be relatively shallow, such as having aratio of width to height of about 3 or more. The height of the resin bed120 in the holding tank 110 can be about 6 inches or more. Inembodiments, the resin bed 120 may have a height less than the height ofthe holding tank 110.

The system 100 can include a plurality of input lines operably coupledto the holding tank 110, such as the plurality of input lines 160 a-160d. The plurality of input lines 160 a-160 d can include a first inputline 160 a operably coupled to a supply of, and configured to deliver, afirst solution (e.g., lithium salt solution) into the resin bed in theholding tank; a second input line operably coupled to a supply of, andconfigured to deliver, a second solution (e.g., caustic solution) intothe resin bed in the holding tank; and at least a third input line—thirdinput line 160 c and fourth input line 160 d—operably coupled to, andconfigured to deliver, water to the into the resin bed in the holdingtank, such as for washing/rinsing the resin bed. The holding tank 110and the input lines 160 a-160 d can be operably coupled together via oneor more valves and conduits configured to provide a selectivelychangeable connection therebetween. For example, one or more valves maybe actuated to cause a solution from the first input line 160 a to flowinto the holding tank 110, and then another set of valves may beactuated to cause a solution from the second input line 160 b to flowinto the holding tank 110, and so on.

In embodiments (not shown), the system can include equipment to washand/or remove at least some of the broken resin beads from the resinbed. The system can include resin back-wash equipment to periodicallyremove broken resin beads from unbroken resin beads. In an embodiment,the system can include vacuum equipment to remove at least a portion ofthe resin bed (e.g., the entire resin bed) from the resin tank viavacuum force and transport the same to the back-wash equipment. Inembodiments, the back wash equipment can include a tank with a conicalbottom having an inlet at the bottom and an overflow outlet at the top.The resin bed can be fluidized (at least 100% bed expansion) with waterentering the back-wash tank from the bottom (up-flow mode) and leavingthe tank from the top outlet, carrying with it the broken (e.g.,attritioned) resin beads as it exits the conical tank. The water exitingthe tank can be directed to a small tank or fluid line with a strainertherein sized to remove the broken resin beads from the water. Thebroken resin beads are separated from the water carrying them in thesmall tank where the strainer retains the broken resin beads, whileallowing the separated water (devoid of broken resin beads) to passthrough and recycle back to the back-wash tank, such as via a pump, tokeep the resin bed fluidized. The unbroken resin beads remain in theconical tank. The resin bed can be backwashed in this manner for atleast one minute such as 1 minute to 1 day, 1 minute to 1 hour, 1 minuteto 10 minutes, 2 minutes to 30 minutes, or less than about 30 minutes.After resin is back-washed, the resin bed left in the back-wash tank(e.g., containing unbroken resin beads) can be transported back to theresin tank, such as by using a vacuum pump. At least one resin back-washsystem can serve more than one train of resin beds in resin tanks of thesystem. In embodiments, such back-washing can be performed periodically,such as weekly, monthly, bimonthly, semi-annually, annually, etc.

A known volume of the resin is held in the tank and is referred to asthe resin bed 120 and its volume is a one bed volume. The processesherein comprise two major steps: in the first major step, the sulfateions are adsorbed from the lithium sulfate feed solution (e.g.,contacting solution) by exchanging them with the hydroxyl ions on theion exchange resin. Such an exchange can be produced bycontacting/soaking (both terms are used herein to provide the samemeaning but are used to imply a different occurrence thereof) the ionexchange resin (having hydroxyl ions bound thereto) with a lithiumsulfate solution first. Subsequently, the ion exchange process isreversed. That is, the sulfate ions on the ion exchange resin aredisplaced by hydroxyl ions by soaking/contacting the resin bed with acaustic (e.g., sodium hydroxide) solution. Between each major step, theresin bed can be washed/rinsed (both terms are used herein to providethe same meaning but differentiate between different occurrencesthereof) with de-ionized water to displace the solutions held in the ionexchange resin pores as much as practical. Water washes/rinses aftereach step may be one or more, using straight wash or split wash methods.

One bed volume of the feed or input solution(s) can be used in each step(sulfate ions removal from the lithium sulfate solution in the firststep and hydroxyl ions removal from the sodium hydroxide solution duringthe second step) to maximize sulfate and hydroxyl ions adsorptions bythe resin bed from their respective feed solutions to produce lithiumhydroxide solution with only trace levels of sulfate from the firstmajor step and sodium sulfate solution with trace levels of hydroxylions from the second major step.

The contact time of any of the solutions with the resin bed can be heldas small as needed, varying from one second to few minutes (e.g., atleast one second, at least 5 seconds, at least 10 seconds, at least 30seconds, at least 1 minute, at least 5 minutes, at least 10 minutes), toachieve as high a number of batches a day as practical.

One complete batch includes the following sequence. In the first majorstep, the resin bed 120 in the hydroxyl form (e.g., having hydroxyl ionsbound thereto) is brought in contact with the lithium sulfate feedsolution (e.g., contacting solution) for a selected time. The firstmajor step can be performed while keeping the resin bed gently moving byagitation (e.g., using an overhead mixer or sonication). Contacting theresin bed with the contact solution (lithium sulfate) can be followed bydraining the contact solution (e.g., solution that is predominantlylithium hydroxide instead of lithium sulfate after the resin bedcontact) from the resin bed into a receiver or container first bygravity and then under vacuum. Draining the resin bed can be followed bywater washing the resin bed once or more, one contact at a time.

In the second major step, the washed resin bed (e.g., washed after thefirst major step) is soaked or brought in contact with a caustic (e.g.,sodium hydroxide) solution of a chosen strength for a given time. Thesoaking can be performed while keeping the resin bed gently moving byagitation such as by an overhead mixer. Soaking the washed resin bedwith the caustic solution can be followed by draining the causticsolution (converted to a sodium sulfate solution via ion exchange duringthe soaking) from the bed into a receiver first by gravity and thenunder vacuum. Draining the caustic solution can be followed by waterwashing the resin bed once or more, one contact at a time. Theconcentration (e.g., molarity) of the lithium salt solution (e.g.,dissolved lithium salts in the contacting solution prior to contact withthe resin bed) can be at least 0.0001 mol/L, at least about 0.1 mol/L,at least about 1 mol/L, or at least 3 mol/L. The molarity of the causticsolution (prior to contact with the resin bed) can be at least 0.1mol/L, such as at least about 1 mol/L, or 3 mol/L or more.

The above steps can be repeated to produce as many batches in a day aspractical.

A total batch time (depending on the process conditions and resin type)could vary from a few minutes to an hour, such as from 30 to 60 minutes,allowing making 24 to 48 batches a day. The equivalence of sulfate ionsloading on the ion exchange resin in the first contact with the lithiumsalt (e.g., lithium sulfate) can vary from a fraction of resinsaturation capacity for sulfate ion to a resin theoretical capacity forsulfate ion depending upon the resin type and process conditions. Forexample the sulfate loading of an anionic resin, reported by one resinsupplier, is about 1 g equiv/l when contacted with one bed volume of onenormal lithium sulfate solution while keeping the sulfate leakage low,at trace levels. The theoretical capacity of this resin may be greaterthan 1.5 g equiv/l. The theoretical capacity of some resins may be about0.75 g equiv/l of resin or more, such as about 0.75 g equiv/1 to 1.5 gequiv/l, or about 1.0 g equiv/1 to 1.5 g equiv/l, or about 1.5 g equiv/1to 3.0 g equiv/l of resin depending upon the resin type. The tracesulfate impurity levels in the lithium hydroxide product solution inthis example can be isolated by using barium hydroxide to precipitatesulfate out as insoluble barium sulfate or by using conventional ionexchange process, such as a water softener system using anion resin bedin OH form instead of cation form. So, by manipulating the bed volumesof the contact solution and its sulfate concentration, selected amountsof sulfate loading on the resin with almost no or only trace leakage ofsulfate, can be achieved in the processes disclosed herein. The higherthe loading on the resin, the smaller the resin inventory required bythe process. However, it could be at the expense of higher sulfateleakage requiring sulfate removal from the lithium hydroxide productlater on, which may or may not be an attractive option. The desorptionequivalence of the counter ions (e.g., sulfate ions) on the ion exchangeresin by hydroxyl ions in the second soaking step would be the same asin the first contact for the sulfate in terms of g equiv/l value.

The lithium hydroxide solution produced from the first major step can befurther processed using standard multiple-effect evaporation to producelithium hydroxide monohydrate from lithium hydroxide solution.

The sodium sulfate solution produced from the second major step can befurther processed to crystallize sodium sulfate product if there ismarket for it. In the case of no market, the option to place the sulfatesolution in an evaporation/tailings pond, temporarily or permanently,can be exercised in this case. Such disposal in an evaporation/tailingspond is just not conceivable in the processes currently employed bysome, as it would lead to lithium values going to the pond as well aswith the sodium sulfate solution, causing substantial lithium loss. Insuch a case, the sodium sulfate crystallization/drying/handling, anddisposal is absolutely required; substantially adding to the capital andoperating costs of the operation.

In some cases, where the lithium sulfate solution is high inconcentration such as greater than one normal or the actual theoreticalexchange capacity or close to it is targeted, a two-stage ion exchangeset-up could be used, wherein the drained solutions from the steps arefurther contacted with another resin bed housed in the second ionexchange set-up, similar to the first, underneath the first set-up(e.g., in series). This configuration would possibly reduce the resinbed volume used in each stage, while possibly increasing the resininventory of the system as a whole and could be an attractive option insome cases.

It is important that the lithium sulfate solution is as pure aspractical to keep the process as simple as possible. If it has cationand anion (e.g., trace) impurities, it might be an attractive option tofirst, pass the solution through a conventional ion exchange system,comprised of cation exchange resin bed in a column in the lithium formand anion exchange resin bed in a column in the sulfate form to removethe impurities, instead of not removing them. The same applies to thesodium hydroxide solution used in the second step if it has significantlevels of both cation and anion impurities. The option to purchase ahigh grade caustic, costing slightly more, is available in this case.

The water washes after each step may ensure that the residual solutions(e.g., the first contact solution (lithium salt solution and/or lithiumhydroxide in the first step), and the second soaking solution (thecaustic solution and/or sodium sulfate solution in the second step))retained by the resin pores are substantially completely displaced bythe wash waters. The split wash method, where the resin bed is firstwashed with the stored washed water generated by the second wash and thesecond wash is done with fresh water, is preferred over the straightwash method as it conserves water. The washed water from the first washin the first major step, the most concentrated wash of all, can eitherbe absorbed in the process as is or can be further concentrated byevaporation or reverse osmosis methods before sending it back to theprocess. The water recovered in either technique is recycled back to domore washes, reducing overall water usage. This water recoverytechnique, or one similar to it, can be employed for all the waterwashes of the two steps, if necessary.

Since it is desirable to have no sulfate presence in the lithiumhydroxide solution produced by the processes disclosed herein, it mightbe possible to achieve that condition by treating trace or residuallevels of sulfate present in the lithium hydroxide solution (e.g., aftercontact of the first solution with the ion exchange resin) with bariumhydroxide to precipitate out sulfate as barium sulfate, which is highlyinsoluble. For sodium sulfate product from the second major step,presence of some hydroxyl ions in this soaking solution after contactwith the ion exchange resin can be removed by using sulfuric acid toconvert it to sodium sulfate.

The choice of the second step contact/soaking solution could bepotassium hydroxide, ammonium hydroxide, etc. instead of sodiumhydroxide producing potassium sulfate and ammonium sulfate by-productsinstead of sodium sulfate if lithium sulfate is the feed solution of thefirst step. If lithium chloride is the feed solution of the first stepinstead of lithium sulfate, then the by-products would be the chloridesof the alkali solution type selected for the second step. The by-productin the contacting/soaking solution can include one or more of sodiumsulfate, potassium sulfate, sodium chloride, potassium chloride, orsodium nitrate, or potassium nitrate.

In examples, the processes disclosed herein may be used to purify alithium hydroxide solution contaminated with one or more anions such assulfate, chloride, nitrate, etc. In such examples, the feed to thesystem would be a lithium hydroxide contaminated solution instead oflithium sulfate solution. In such examples, the lithium sulfatesolutions in the processes disclosed herein may be substituted with alithium hydroxide solution and vice versa.

The disclosed process is simple as it uses equipment familiar to theoperators and does not require special skills to operate it. Theelectrochemical process it replaces is a highly specialized process andrequires specially trained and skilled workers to operate it. Thedisclosed process potentially offers a huge advantage in capital costsavings. It uses relatively less expensive equipment such as few tanks,mixers, pumps, low resin inventory, and reverse osmosis units ascompared to the equipment used by an electrochemical system whichrequires electrochemical cells with anodes and cathodes, cationmembranes between the electrodes, frames holding the cells together,heavy copper bus-bars, rectifier, chiller or cooling tower, network ofpiping, advance instrumentation and control equipment, more elaborateand expensive system installation, etc. While the actual cost estimatesof the two systems cannot be determined without carrying out their coststudies, it is evident from the type of equipment used by each that thedisclosed process would potentially be significantly lower in capitalcost than the electrochemical process. For a production plant producingten million kilos of lithium hydroxide monohydrate annually, thepotential savings in the capital cost are estimated to be in the milliondollars. For the stated production rate, assuming 24 batches a day andsulfate loading of 1 g equiv/l on the resin, the resin volume requiredis estimated to be about 1000 cu ft., which could be housed in 6 to 10parallel trains of the disclosed ion exchange system, each accommodatingabout 100 to 150 cu ft. of resin bed. Comparatively, for theelectrochemical system, it is estimated, would require about 250 cellswith anodes, cathodes, and cation membranes (each 2.7 M² in area),frames holding the cells, substantial and elaborate cooling systems todissipate heat generation, fairly good size rectifiers and bus bars,complicated network of piping system, advance instrumentation andcontrol system to ensure safe operation, fairly good size exhaust systemto vent oxygen and hydrogen gases generated by the process, especiallythe hydrogen gas which is flammable and requires significant airdilution before safe atmospheric discharge if it is not captured forfuel or energy source.

In examples, the processes disclosed herein, or any portions thereof,may be carried out substantially simultaneously in a Higgins Loopcontactor, where resin flows counter current to the solution. Inexamples, the processes disclosed herein, or any portions thereof, maybe carried out substantially simultaneously in a carousel system whereone or more containers with resin beds (on the carousel) are movedinstead of resin therein.

The disclosed process will have an advantage in the operating cost aswell. The cost of the chemicals used by the proposed process forproducing lithium hydroxide from the lithium carbonate salt for example,sulfuric acid and sodium hydroxide, amounts to between 30 to 40 centsper kg of the product (lithium hydroxide monohydrate) without creditingfor the revenue of the by-product, sodium sulfate. This cost can be cutby almost half (e.g., 15 to 20 cents/kg of product) if the lithiumsulfate solution is generated by acid leaching of lithium oreconcentrate instead of lithium sulfate generated from acidifying lithiumcarbonate. While the electrochemical process does not use any chemicals,it produces one instead: sulfuric acid when doing lithium sulfateelectrolysis. The significant operating cost in this process, comparedto the disclosed chemical process, is the power cost which is estimatedat over 4 or 5 kwh/kg of product, such as between 4.5 to 5.25 kwh/kg ofproduct. Depending on the unit price of electricity, the power cost inmany locations could be much higher than the chemical costs noted hereinfor the proposed process. The maintenance cost is another cost item,where the disclosed process is likely to have a lower maintenance cost.

Though an accurate comparison of operating costs of the two processescannot be estimated without doing a detailed cost study, it is apparentthat the disclosed process would provide some cost savings in theoperating cost as well.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments are contemplated. The various aspects andembodiments disclosed herein are for purposes of illustration and arenot intended to be limiting.

What is claimed is:
 1. A method of producing lithium hydroxide fromlithium salts, the method comprising: contacting a resin bed includinganion exchange resin having hydroxyl ions bound thereto with acontacting solution having dissolved lithium salts therein for aduration of time effective to at least partially exchange anions of thedissolved lithium salts with the hydroxyl ions bound to the anion resin;draining the contacting solution from the resin bed to collect a productsolution including at least some lithium hydroxide therein; washing theresin bed with water effective to displace any residual contactingsolution from the anion exchange resin; soaking the resin bed with acaustic solution effective to displace anions of the dissolved lithiumsalts from the anion exchange resin with hydroxyl ions of the causticsolution; and draining the caustic solution from the resin bed tocollect a by-product solution.
 2. The method of claim 1, furthercomprising rinsing the resin bed with water effective to displace anyresidual caustic solution from the anion exchange resin.
 3. The methodof claim 2, further comprising repeating the contacting, draining,washing, soaking, draining, and rinsing one or more times.
 4. The methodof claim 2 wherein one or more of washing or rinsing includes using avolume of fresh water at least equal to a volume of the resin bed. 5.The method of claim 2, wherein rinsing the resin bed with water includesproviding a contact time of water with the resin bed of at least onesecond.
 6. The method of claim 1, wherein the resin bed is housed in aholding tank having an agitator and drain.
 7. The method of claim 6,wherein the agitator is an overhead agitator.
 8. The method of claim 6,further comprising agitating the resin bed with the agitator during oneor more of the contacting, draining, washing, soaking, or draining. 9.The method of claim 6, wherein agitating the resin bed with the agitatoris carried out such that the agitator does not result in damage to theresin bed or splashing.
 10. The method of claim 1, wherein contacting aresin bed including anion exchange resin having hydroxyl ions boundthereto with a first contacting solution includes contacting the anionexchange resin with one or more of a lithium sulfate solution, a lithiumchloride solution, or a lithium nitrate solution.
 11. The method ofclaim 10, wherein the by-product solution includes one or more of sodiumsulfate, potassium sulfate, sodium chloride, potassium chloride,potassium nitrate, or sodium nitrate.
 12. The method of claim 1, whereinone or more of draining the contacting solution from the resin bed tocollect a product solution including at least some lithium hydroxidetherein or draining the caustic solution from the resin bed to collect aby-product solution can include draining the contacting solution or thecaustic solution by one or more of gravity or under vacuum.
 13. Themethod of claim 1, wherein the contacting solution has a concentrationof dissolved lithium salts that is at least about 0.0001 mol/L, prior tocontacting the resin bed.
 14. The method of claim 1, wherein causticsolution has a concentration that is at least about 0.1 mol/L, prior tocontacting the resin bed.
 15. The method of claim 1, wherein a volume ofthe caustic solution used to soak the resin bed is at least equal to avolume of the resin bed.
 16. The method of claim 1, wherein thecontacting solution contacts the resin bed for at least one second. 17.The method of claim 1, wherein the caustic solution soaks the resin bedfor at least one second.
 18. The method of claim 1, wherein a volume ofwater used to wash the resin bed is at least equal to a volume of theresin bed.
 19. The method of claim 1, wherein washing the resin bed withwater includes washing the resin bed with a volume of water is at leastequal to a volume of the resin bed, using split-wash technique.
 20. Themethod of claim 1, wherein washing the resin bed with water includesproviding a contact time of water with the resin bed of at least onesecond.
 21. The method of claim 1, further comprising removing one ormore of cation or anion impurities, other than lithium and sulfate ions,from the contacting solution, prior to contacting the resin bed with thecontacting solution.
 22. The method of claim 1, further comprisingremoving one or more of cation or anion impurities, other than sodiumand hydroxide ions, from the caustic solution, prior to soaking theresin bed with the caustic solution.
 23. The method of claim 1, furthercomprising precipitating residual sulfate ions out of the productsolution using a barium hydroxide solution.
 24. The method of claim 1,further comprising reacting residual hydroxide ions out of theby-product solution using an acid.
 25. The method of claim 1, wherein aresin bed height is greater than about six inches.
 26. A system forproducing lithium hydroxide from lithium salts, the system comprising: aholding tank having a height and at least one drain; a resin bedincluding an anion exchange resin therein, the resin bed having a heightless than or equal to the height of the holding tank, the anion exchangeresin including hydroxide ions bound thereto; a retention memberdisposed in the holding tank between the resin bed and the at least onedrain, the retention member being configured to retain the resin bed inthe holding tank; a plurality of input lines, including: a first inputline operably coupled to a supply of, and configured to deliver, alithium salt solution into the resin bed in the holding tank; a secondinput line operably coupled to a supply of, and configured to deliver, acaustic solution into the resin bed in the holding tank; at least athird input line operably coupled to, and configured to deliver, waterto the into the resin bed in the holding tank; a plurality of outputcontainers, including: a first output container configured to hold alithium hydroxide solution produced in the resin bed from interactionthereof with the lithium salt solution; a second output containerconfigured to hold a sodium salt solution produced in the resin bed frominteraction thereof with the caustic solution; and at least a thirdoutput configured to hold one or more of a wash or rinse solution fromthe resin bed; and one or more valves and fluid lines operably coupledto the first input line, the second input line, the at least a thirdinput line, the first output container, the second output container, theat least a third output container, and the holding tank.
 27. The systemof claim 26, further comprising at least one vacuum pump operablycoupled to one or more of the drain or the first output container, thesecond output container, and the at least a third output container. 28.The system of claim 26, further comprising at least one agitatorpositioned and configured to agitate the resin bed.
 29. The system ofclaim 26, wherein the at least one agitator includes an overheadagitator positioned and configured to stir the resin bed.
 30. The systemof claim 26, wherein the holding tank is configured to be drained viaone or more of gravity feed or vacuum force.
 31. The system of claim 26,wherein the system includes a plurality of holding tanks each arrangedin series such that a first holding tank having a first resin bedtherein can be drained into at least a second holding tank having asecond resin bed therein.
 32. The system of claim 31, wherein theplurality of holding tanks are arranged and positioned such that eachholding tank can feed subsequent holding tank with a solution drainedtherefrom via one or more of a gravity feed or vacuum force.
 33. Thesystem of claim 26, wherein the system includes equipment forback-washing the resin bed to remove broken resin beads.
 34. The methodof claim 1, wherein the contacting, the draining, the washing, thesoaking, and the draining are carried out substantially simultaneouslyin a Higgins Loop contactor, where resin flows counter current to thesolution.
 35. The method of claim 1, wherein the contacting, thedraining, the washing, the soaking, and the draining are carried outsubstantially simultaneously in a carousels system where one or morecontainers with resin beds are moved instead of resin therein.
 36. Themethod of claim 1, wherein the contacting solution includes a lithiumhydroxide solution contaminated with an anion such as sulfate, chloride,or nitrate.